Process for the cracking of hydrocarbon oils and the like



J. NELSON. PROCESS FOR THE CRACKING OF HYDROCARBON} OILS AND THE LIKE.APPLICATION FILED DEC.23, 1919.

1,391,5 9, Patntedsept. 20,1921.

INVENTOR J. NELSON. PROCESS FOR THE CRACKING OF HYDROCARBON 0|LS AND THELIKE. APPLICATION FILED DEC.23| 1919.

1,391,569 Patented Sept. 20, 1921.

2 SHEETS-SHEET 2.

INVENTOR UNITED. STATES PATENT orrlcs.

- JOHN NELSON, 0F GLASGOW, SCOTLAND.

' rnocns's non THE cnncx'me or HYDROCARBON OILS AND THE LIKE.

Specification of Letters Patent. Pate t d S t 20 1921 Application filedDecember 23, 1919. Serial No. 346,990.

To all whom it met concern:

Be it known that J 0111s NELSON, a subject of the King of England,residing in Glasgow, Scotland, have invented certain new and usefulImprovements in a Process for the Cracking of Hydrocarbon Oils and thelike, of which the following is a speci- "contact-substance, and coolingthe vapors prior to further treatment with the contact material.Preferably, the vapors are cooled to a temperature just above that ofcondensation before the succeeding cracking step. For many oils, thetemperature throughout the process does not substantially exceed 620 C.and is preferably about 500550, and the maximum cooling of the vaporsbetween successive treatments is re resented by a temperature of about375. T e degree of cooling between successive steps need not be thesame, but may be .varied according to circumstances, for example, theextent o which the vapors have been already cracked. It is preferred toeffect the cracking of the oil in a series of steps, each step being ofcomparatively short duration. 1 The temperature of the contact-substancemay be the same for each period of contact, or a decreasing orincreasing temperature may be employed. The contact material is keptagitated during the process as, for'example, by the passage of thehydrocarbon. According to a modification of the invention, the oil orits vapors are submitted to the action of the liquid contact-substancein conj unction with steam;

If the oil to be cracked'contains tarry or other objectionable productswhich cannot be eliminated during the cracking process,

the oil may be distilled from an auxiliary vessel, and the distillate orvapors subjected to the cracking operation.

The contact material may be a .molten metal, or alloy, for example,molten lead,

or a fused salt, or mixture of salts, as sodium mtrate, or sodiumhydroxid, but the invention is, of course, not restricted in re- Y spectto the use of a particular liquid contact-substance. I I

The extent of the cracking may be varied wlthln certain limits byvarying the depth at wh ch the hydrocarbon or its vapors are dellveredbeneath the surface of the contact substance, and by the number ofcontact periods. As one object of the invention is to avo1d productionof much carbonaceous matter, 1t is material not to subject the oil or1ts vapors to the cracking temperature in constricted channels Theapparatus which forms the subject of my prior application affordsspecial provision against this, as well as providing a means ofoperation of the process herein set forth.

The accompanying drawings show one form in sectional elevation of suchapparatus set for the treatment of two different kinds of oil.

Figure 1 shows diagrammatically the arrangement when heavy oils of highboilingpoint, such as petroleum fuel oils, are to be treated, and

Fig. 2 shows the setting for the treatment of lighter oils, such ascoal-tar naphthas,

boiling say, above 160 and under 240 C.

Referring to the drawings, A represents the heating chamber having fourcrackin pots B, set in the flue C, of the furnace As shown, thearrangement is such that the chamber in which the pots are set issurrounded by the hot gases from the furnace. The flue C in which thecracking-pots are set may be divided above the level of thecontact-substance in the pots with a transverse partition, as indicatedby the chain lines in Fig. 1, to restrict theheating area in the pots. Eis the inlet for the hydrocarbon, and F are the pipes which lead thevapors from one pot to the next. f-g represents the-level of the moltencontact-substance, "gh the zone of partial cooling, and

are shown touching the crown G, of the furnace, the cooling area in thiscase being merely that derived from the depth of the furnace crown addedto theheight above the latter of the pipe, and, to a lesser degree, tothe distance from the crown to the surface of the contact-substance. Thefigure illustrates, therefore, the minimum degree of intermediatecooling for heavy hydrocarbon vapors between successive stages oftreatment.

In the case of lighter oils, such as the coal-tar naphthas mentioned,the flanges of the cracking-pots are not flush with the furnace-crownsetting, but extend out of the furnace as shown in Fig. 2. In the caseof petroleum solar-oil, a similar variation would be made in order tosecure the maximum cracking results. It is, of course, to be understoodthat there is necessarily a limit beyond which the communicating pipesbetween the cracking pots project beyond the sphere of heat, and thedistance must never be so great that condensation to liquid of'thehydrocarbon vapors can take place between successive treatments. Thecooling is preferably the maximum possible in order to obtain thegreatest temperature difference between the vapor and thecontact-substance. The selection of the particular contactsubstance tobe used depends, among other considerations, upon the workingtemperature employed. In operating at moderate temperatures (such as areutilized in the production of volatile spirits for use in petrolengines) it is preferred to make use of a bath of molten lead or ofsalts of suitable melting point, and to pass the hydrocarbon oritsvapors into the bath at a suitable distance below its surface. Iftemperatures exceeding those at which lead can be satisfactorilyemployed are required, metals or alloys of higher melting point thanlead may, of course, be used.

It has been found that if oil be cracked by the aid of a liquidcontact-substance in a series of successive steps, each step being ofcomparatively short duration, and the oil vapors be subjected to acooling action prior to treatment in one or more further 7 steps, a muchmore satisfactory conversion of the oil can be obtained than hashitherto been the case. It is to be understood, however, that the totalperiod of contact between the oil and the contact-substance is notnecessarily short; it maybe prolonged as desired to secure the maximumdegree of conversion under the particular conditions of working; it iseach step of'contact which is short.

As the time during which the hydrocarbon and its product remain incontact with-the hot liquid substance is brief, the whole product or anydesired fraction thereof, may be subjected to one or more re-treatments;

and desire vapors to a point just above that atwhichthey condense. 1

2. The herein described process for 'crack ing hydrocarbon oils and thelike which comprises introducingthe hydrocarbon into a liquid metalliccontact substance in a series .of steps and between two successive stepscooling the vapors to a point just above that at which they condense.

3. The herein described process for cracking hydrocarbon oils and thelike which comprises introducing thehydrocarbon and steam into a liquidcontact substance in a series of steps and between two successive stepscooling the vapors to a point just above that at which they condense.

4E. The hereinjdescribed process for cracking hydrocarbon oils and thelike which com"- prises introducing the hydrocarbon into a liquidcontact substance in a series of steps of brief contact period andbetween two successive steps cooling the vapors to a point just abovethat at which they'condense.

i 5. The herein described process for cracking hydracarbon oils and thelike which comprises introducing the hydrocarbon into a liquid contactsubstance at a temperature of v between two successive steps cooling thevapprs t8 a temperature not substantially below 7. The herein describedprocess for cracking hydrocarbon oils and the like which comprisesintroducing the hydrocarbon into a, liquid metallic contact substance ata temperature of 500550 in a series of steps and between two successivesteps cooling the vapors to a point just above that at which theycondense.

8. The herein described process for cracking hydrocarbon oils and thelike which comprises introducing the hydrocarbon into a liquid metalliccontact substance at a temperature not exceeding 620 in a series of.

steps and between two successive steps cooling the vapors to atemperature not subvapors of the h drocarbon to a point just stantiallybelow 375 0. above that at which they condense, and vary- 9. The hereindescribed rocess for crack ing the temperature of the contact substance10 ing hydrocarbon oils an the like which at difierent steps. 5comprises introducing the hydrocarbon into In testimony whereof I afiixmy signature.

a liquid contact substance in a series of steps and between twosuccessive steps cooling the J NO. NELSON.

